Santos Rute, Valamatos Maria João, Mil-Homens Pedro, Armada-da-Silva Paulo A S
Faculdade de Motricidade Humana, Universidade de Lisboa, 1499-002 Estrada da Costa, Portugal.
Coimbra Health School, Polytechnic University of Coimbra, Rua da Misericórdia, Lagar dos Cortiços, S. Martinho do Bispo, 3045-093 Coimbra, Portugal.
Sports (Basel). 2024 Jul 31;12(8):211. doi: 10.3390/sports12080211.
Supersonic shear image (SSI) ultrasound elastography provides a quantitative assessment of tissue stiffness using the velocity of shear waves. SSI's great potential has allowed researchers in fields like biomechanics and muscle physiology to study the function of complex muscle groups in different conditions. The aim of this study is to use SSI to investigate changes in the stiffness of the vastus lateralis (VL) muscle as a consequence of passive elongation, isometric contraction, and repeated muscle activity. In a single session, 15 volunteers performed a series of isometric, concentric, and eccentric contractions. SSI images were collected from the VL to assess its stiffness before and after the contractions and at various knee angles. Two-way within-subjects ANOVA was used to test the effects of muscle contraction type and knee angle on VL stiffness. Linear regression analysis was employed to assess the relationship between muscle stiffness and the intensity of isometric contractions. After maximal contractions, VL stiffness increased by approximately 10% compared to baseline values, and following maximal isometric ( < 0.01) and eccentric contractions ( < 0.05). Yet, there was no change in VL shear modulus at the end of concentric contractions. The relaxed VL shear modulus increased with knee flexion both before and after the knee extensor contractions ( < 0.001). A linear relationship between the shear modulus and the degree of isometric contraction was observed, although with notable individual variation (R = 0.125). Maximal contractile activity produces modest increases in relaxed muscle stiffness. The SSI-measured shear modulus increases linearly with the degree of isometric contraction.
超音速剪切图像（SSI）超声弹性成像利用剪切波速度对组织硬度进行定量评估。SSI的巨大潜力使生物力学和肌肉生理学等领域的研究人员能够在不同条件下研究复杂肌肉群的功能。本研究的目的是使用SSI来研究股外侧肌（VL）在被动拉伸、等长收缩和重复肌肉活动后的硬度变化。在一次实验中，15名志愿者进行了一系列等长、向心和离心收缩。从VL采集SSI图像，以评估收缩前后以及不同膝关节角度下其硬度。采用双向受试者内方差分析来测试肌肉收缩类型和膝关节角度对VL硬度的影响。采用线性回归分析来评估肌肉硬度与等长收缩强度之间的关系。最大收缩后，与基线值相比，VL硬度增加了约10%，在最大等长收缩（<0.01）和离心收缩后（<0.05）也是如此。然而，向心收缩结束时VL剪切模量没有变化。在伸膝收缩前后，放松状态下的VL剪切模量均随膝关节屈曲而增加（<0.001）。观察到剪切模量与等长收缩程度之间存在线性关系，尽管个体差异显著（R = 0.125）。最大收缩活动使放松肌肉硬度适度增加。SSI测量的剪切模量随等长收缩程度呈线性增加。
